BLADAPTION: Model adaptation of generic rotor blades for lifetime extension assessments using optical 3D measurement techniques and experimental modal analysis

At a glance

• Continued operation of wind turbines after expiry of their design lifespan can represent an alternative to decommissioning for operators. A decision is taken on the basis of assessments regarding the predicted remaining lifespan.
• The methods currently employed for the preparation of assessments are subject to uncertainties which can result in high safety margins. Information regarding the components, especially the rotor blades, is often lacking.
• In the BLADAPTION project, the scientists are developing a procedure integrating measurement  data into existing simulation models with the aim of making more reliable predictions.

The challenge

Wind turbines in Germany are subsidized for 20 years with a fixed remuneration for the electricity in accordance with the German Renewable Energy Sources Act (EEG). Thereafter, operators are faced with the decision of whether to continue operating the turbine or whether it must be decommissioned. This decision is based on lifetime extension assessments, which predict the remaining lifetime, taking the critical components into consideration. The calculations utilize a simulation model of the full turbine.

In most cases, there is no detailed material, structural, or geometric information available for the assessment, especially for the rotor blade. However, the rotor blades’ properties play a decisive role in the full turbine simulation. The resulting uncertainties can lead to high safety margins in the assessments. 

The solution

In the BLADAPTION project, the research institutes and companies involved are developing a procedure for the reliable preparation of lifetime extension assessments taking the rotor blades’ properties into consideration more efficiently. It is based on measurement data from the field, information about the condition of the rotor blades, and wind data at the site. They are used via an optimization architecture to determine discrete structural details and thereby enable the approximation of an underlying calculation model to reality. One goal of the method development is to minimize wind turbine downtime and thus costs, which significantly increases the acceptance of the method among turbine operators.

Fraunhofer IWES is responsible in a subproject for the development of the methods employed for the model adaptation. This includes the reconstruction of the turbine characteristics from the field measurements and the development of a validated procedure for the preparation of a lifetime extension assessment with reliable statements on the remaining lifetime.

The added value

The project thus provides a valuable tool for wind farm operators who want to operate their turbines reliably long beyond their design lifespan. As it is not always possible to replace them, continued operation represents a viable option. BLADAPTION provides a sound basis for decision-making with lower safety margins for operators and, at the same time, enables the continued operation of functional wind turbines for as long as possible, thus saving resources and producing more climate-friendly electricity.